noun ( pl. raphae pronunc. same) Anatomy & Biology
a groove, ridge, or seam in an organ or tissue, typically marking the line where two halves fused in the embryo, in particular
• the connecting ridge between the two halves of the medulla oblongata or the tegmentum of the midbrain
• Botany a longitudinal ridge on the side of certain ovules or seeds
• Botany a longitudinal groove in the valve of many diatoms
